Guy on baking

Air fryers versus ovens

Despite their name, air fryers bake their food rather than frying it. In effect, they are simply small fan-forced ovens. The key difference between air fryers and ovens is simply size.

Because of their smaller size, air fryers typically take less time to heat the air and also have more rapid air flow. This, in turn, means that they typically cook faster than fan-forced ovens, say 25-50% faster. Furthermore, the use of a basket in which the food is placed, helps air flow and thus evenness of the cooking. They also use less energy, occupy less space and heat up the kitchen less.

Because of their larger size, ovens can cook multiple dishes at the same time. They can also cook in ways other than fan-forced and are therefore more flexible.

Finally, you will almost definitely already have an oven but may well not (yet) have an air fryer.

Baker’s yeast versus sourdough starter

Baker’s yeast is a particular species of yeast, Saccharomyces cerevisiae, which converts sugar into carbon dioxide and ethanol. The carbon dioxide gas causes the dough to rise, whilst the ethanol either evaporates or is left in the bread. The heat used whilst baking then kills off the yeast. It is the same species, but a different strain, as that used in alcoholic fermentation. It is a manufactured product, grown in vats. It has only been around for the last 150-250 years.

Baker’s yeast is available in a number of different forms, the main differences being the moisture content. The most common form for non-commercial bakers in Australia is ‘dry yeast’, where live yeast cells are encapsulated in a thick jacket of dry, dead cells with some growth medium. Before use, dry yeast is re-hydrated, such that the live yeast can escape its jacket. Note that nutritional yeast is ‘deactivated’ (i.e. dead) Saccharomyces cerevisiae, which is eaten for its taste or nutritional value.

A sourdough starter is a much more complicated substance than baker’s yeast. Whilst it will usually contain Saccharomyces cerevisiae, it will also contain a variety of other yeasts. It will also contain lactic acid bacteria, which convert carbohydrates into lactic and other acids plus other substances (it is these acids that give sourdough its sour/tangy taste). And the yeast and bacteria will be in a mixture of flour and water, on which they have been feeding.

A sourdough starter is created by simply mixing flour and water together and leaving it loosely covered but out in the open, after which various yeasts and lactic acid bacteria will, over time, enter from the air and start to feed and breed. Then, regularly remove around half of the starter and add new flour and water, so that the yeasts and bacteria have something new to eat.

Because baker’s yeast is a single substance, the results from using it are very predictable. It will rise bread faster than a sourdough starter. It is also easily available, easy to use and has a long shelf life.

Because a sourdough starter is a mix of substances which will differ somewhat from starter to starter, its results are less predictable. It also imparts a taste to the bread, which some/many people prefer, and results in a chewier texture. There is general agreement that sourdough starters, and more generally long-time fermentation processes, improve bread digestibility. They may also break down some of the gluten. However, a sourdough starter will rise the bread less quickly (and sometimes much less quickly) and requires time and effort to create and maintain.

Baker’s yeast and sourdough starter are interchangeable in most recipes, but non-trivially so. One rule of thumb is that 100g sourdough starter equates to around 3½g (1+ teaspoons) baker’s yeast plus 50g wet ingredients plus 50g dry ingredients.

Baking soda versus baking powder

Baking soda is sodium bicarbonate (aka bicarbonate of soda). When it is brought into contact with an acid, a chemical reaction occurs that produces bubbles of carbon dioxide which, in turn, have a leavening effect.

Baking powder comprises a base (most commonly baking soda) plus a dry acid (most commonly cream of tartar) plus a buffer (most commonly corn starch) to stop the base and the acid interacting. When it is brought into contact with a liquid, the same chemical reaction occurs as for baking soda.

Most current baking powders produce further carbon dioxide when heated and are thus known as double-acting baking powders.

Wikipedia lists 3 common bases for baking powder and 9 common acids.

Baking soda and baking powder can potentially be substituted for each other but only if you know what you are doing.

Baking soda and baking powder work much more quickly than yeast and don’t produce any flavours. Although yeast also leavens through the production of carbon dioxide, the underlying chemistry is completely different.

Baking powder was invented in 1843 by someone called Alfred Bird, who was motivated to develop a yeast-free leavener because his wife was allergic to yeast. He also invented egg-free custard as his wife was also allergic to eggs. What a husband!

Cornstarch versus cornflour

In Australia and the UK, the words cornstarch and cornflour are used interchangeably to refer to the starch derived from corn grain.

In the USA, however, the word cornflour is used to refer to a flour made from corn kernels.

Honey versus sugar

Sugar is 50% fructose and 50% glucose. Honey is around 40% fructose, 30% glucose, 20% water and 10% other substances (including pollen and minerals). So, whereas sugar is a simple substance, honey is much more complex.

Because of the 10% of other substances, honey has a taste that goes beyond sweetness and this means, for example, that baked goods taste somewhat different if made using honey rather than sugar. Some of these other substances in honey may also have some health benefits.

In sugar, the fructose and glucose are bound together to form sucrose. In honey, however, the fructose and glucose are mostly unbound. One byproduct of this is that honey actually tastes sweeter than sugar.

Honey has an ability to retain moisture and baked goods made using honey may stay therefore moist and tender for longer periods of time than those made using sugar. This can be important for recipes where dryness is a concern, such as whole-grain bread or muffins.

Honey is about 50% heavier than sugar.

When substituting honey for sugar in a recipe, the formulae to use are not obvious because, as discussed above, honey has less sugars but tastes sweeter and is much heavier. A brief survey of the Internet suggests that substituting equal weights (not volumes) is reasonable. Because of the 20% water in honey, reduce the liquid in your recipe by a fifth of a cup for every cup of honey used. And potentially add a bit of baking soda to counteract the acidity of the honey.

Sour cream versus yoghurt

Sour cream and yoghurt are both fermented dairy products, with sour cream being fermented cream and yoghurt being fermented milk. They typically use different bacteria for the fermentation, which gives them somewhat different tastes. Creme fraiche is effectively a type of sour cream. Greek yoghurt is yoghurt that has been strained to remove some of its whey, thus making it thicker (and more similar in consistency to sour cream).

In both cases, the bacterial fermentation turns the sugars into lactic acid.

The differences between sour cream and yoghurt are less than the differences between some cheeses – it is effectively a historical accident that, unlike cheese, they have completely different names.

Because of their different source substance (cream versus milk), sour cream has much more fat (and therefore calories) than yoghurt. By contrast, it typically has less protein.

It is widely agreed that sour cream and yoghurt can be substituted for each other in recipes using a 1:1 substitution. However, note that:

• The flavour might be slightly different.
• Greek yoghurt is the closest in texture to sour cream.
• You can effectively turn plain yoghurt into Greek yoghurt by straining out some of the whey using a piece of cheesecloth.
• Having less fat, yoghurt is more likely to curdle when heated.
• When substituting yoghurt for sour cream, you can also add some butter to raise the fat content.

Possible vegan substitutes for sour cream include:

• Coconut cream, created by skimming off the top of coconut milk and adding some acid (e.g. vinegar or lemon juice) and salt.
• Silken tofu, where you blend firm silken tofu with some acid (e.g. vinegar or lemon juice).

Sugar: brown vs white vs caster vs icing vs raw

White sugar is basically 100% sucrose (C₁₂H₂₂O₁₁), where it has been produced by ‘refining’ either beet sugar or cane sugar to remove the molasses and other substances. It is a crystalline substance, which comes in various crystal sizes. The largest crystal size is usually called granulated or table sugar, the next size down is usually called caster or superfine sugar, and the smallest crystal size is usually called icing or powdered sugar. Icing sugar often also has a small amount (2-5%) of anti-caking agent, such as corn starch, added to prevent clumping.

Brown sugar basically comprises sucrose (at least 90%) plus molasses (3-10% by weight). Traditionally, it was produced by only partially refining either beet sugar or cane sugar, with a number of named varieties depending on the precise process used (e.g. demerara, muscovado, rapadura and turbinado). Nowadays, however, brown sugar is often produced by adding back in sugarcane molasses to completely refined white sugar, with two main varieties (light brown and dark brown) depending on the amount of molasses.

Molasses (which is a singular noun, not plural) is a complex substance comprising around 75% carbohydrates, 22% water and 3% other things. As well turning the sugar brown, the molasses make it moister and softer.

Finally, there is ‘raw sugar’. Different people seem to use the term ‘raw sugar’ to describe slightly different things but the most common usage is that it is ‘partially refined’ sugar, where most of the molasses has been removed but the sugar has not been bleached.

In baking, let’s assume that the default is to use white granulated/table sugar, if only because of the cost. The question then becomes when should you potentially use the other sugars.

Caster sugar tastes the same as table sugar but, because of its smaller crystals, it dissolves more easily. This usually doesn’t make much difference but it does make caster sugar arguably more suitable in cases such as syrups, glazes, frostings, fillings and delicate pastries (such as sponge cakes). Caster sugar is a bit denser than table sugar so, if you are being accurate, recipe substitution should be by weight rather than by volume.

As the name suggests, icing sugar is usually used for icings, frostings or dustings. Also, because it dissolves the most easily of the white sugars, some people keep it on hand to add to drinks. Again, any recipe substitution should be by weight. Icing sugar may contain some corn starch or similar as an anti-caking agent, in which case it is sometimes called that ‘icing mixture’ or similar; this can lead to somewhat unexpected results when baking.

In comparison with white sugar, the molasses in brown sugar give it both a somewhat different flavour and a somewhat different texture. It also caramelises more readily. The American Sugar Association recommends using dark brown sugar in recipes that have a “richer flavour profile such as spice cakes, gingerbreads and barbecue sauces. On the other hand, recipes calling for light brown sugar include sweet sauces, marinades and rubs.” For texture reasons, brown sugar is also sometimes used as a topping over puddings. Because brown sugar is nearly all sucrose, recipe substitution with white sugar can be 1:1 by weight.

Alternatives to sugar divide into two main groups: 1) substances which contain a lot of sucrose/glucose/fructose but which have been made from plants other than sugarbeet or sugarcane; and 2) non-sugar sweeteners. The obvious substance in the first group is honey (as discussed in an earlier section of this page), with other possibilities including coconut sugar, dates, fruit purees, maple syrup, maple sugar and palm sugar. Non-sugar sweeteners are substances which taste sweet to humans but do not contain any sucrose/glucose/fructose. Examples include the synthetic saccharin and the natural stevia. Substituting any of these for table sugar in a recipe is non-trivial.